reasons for dbw throttle not working?

[Bigbore500r]

On a Gen III setup, DBW Throttle body and TAC module must match. i.e.- Corvette throttle body must use a corvette TAC, truck TB must use a truck TAC**. However, you can use a truck or corvette pedal with either setup. The only difference is in the wiring between the TAC and Pedal. If mis-matching a truck pedal to a corvette TAC (or vise versa) there are two wires that must be transposed. I dont have a schematic in front of me at the moment, but I can look it up. Typically, i use a truck TB and TAC, with a vette pedal. Sometimes my harness builder forgets to switch the two wires and it is inoperable untill I switch them. It will throw a DBW related code when this happens though, as pedal position is not reading in sync with TB and commanded pedal position.


**early 2001 / 2002 Tahoe and suburban DBW motors use a corvette style TAC, with a unique throttle body that looks like a corvette but with the motor on opposite side

[goob8869]

Originally Posted by Mike Norris

As mentioned before, I would be checking for codes before buying and throwing parts at it.

What harness do you have (company done by)? I have seen plenty of GM and other companies harnesses have issues out of the box. The exception is Speartech as they test each harness on an engine.

Are all the parts from the same vehicle (pedal, TAC module, ECM)? Not all of these parts from different vehicles are compatible. Some are, but not all.

So check the codes and compatibility first.

Mike Norris

PSI did the harness and they have sent me another harness from the tach to the pedal to see if it changes anything. Everything is out of the same car except the pcm but it was copied from the original. I'm going to see what the harness does when I get it and go from there

[Musclerodz]

The car we are currently finishing had a similar issue and finally figured out the harness at the pcm was pinned incorrectly.

[Dipped]

I had a very similar issue with my car. Idle but zero throttle. After completing an ECU scan it ended up being my throttle position sensor. (gas pedal) Bought a new one from Rockauto for $43.00 and completely resolved the problem.

[goob8869]

OK this is what has been going on. I finally got the scan done and it said the tac module was bad. So I purchased another one and still the same thing happening and the scan still says tac module. Need more help please running out of patience with this real quick.

[oldgoat]

What is the entire combination of parts out of?
Pedal assembly -
Tac Module -
TB -
PCM -

I spent a lot of time experimenting with various throttle bodies, TAC modules and pedals recently. Some do not play well with others as you may be experiencing.
I have proven that several combinations others said could not possibly work do and others many swore worked (though they could cite no examples) do not.
I am happy to lend my experiences.